Method and Apparatus for Image-Based Navigation

ABSTRACT

A system and method for a procedure that can be performed on an appropriate subject. Procedures can include assembling any appropriate work piece or installing members into a work piece, such as an airframe, autoframe, etc. Regardless of the subject, generally the procedure can have a selected result that is efficacious. The efficacious result may be the desired placement of a device. The system and method can be used in confirming an efficacious result.

CROSS-REFERENCE TO RELATED APPLICATIONS

The application is a continuation of U.S. application Ser. No.17/096,211 filed on Nov. 12, 2020, is a continuation of U.S. applicationSer. No. 16/258,864 filed on Jan. 28, 2019, now U.S. Pat. No. 10,838,577issued on Nov. 17, 2020, is a continuation of U.S. application Ser. No.15/141,331 filed on Apr. 28, 2016, now U.S. Pat. No. 10,191,615 issuedon Jan. 29, 2019. The entire disclosures of the above applications areincorporated herein by reference.

FIELD

The subject disclosure relates to a system for performing a procedure,and exemplarily relates to a system to incorporate imaging of a subjectduring performing a surgical procedure on a subject.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

The images of a subject may be acquired prior to a procedure and intra-or post-operatively or post-procedurally. For example, image data can beacquired of a patient and a three-dimensional model of the subject canbe generated based upon the acquired image data. The three-dimensionalmodel can be used for various purposes, such as planning a procedure onthe subject including selecting an implant (if an implant is to bepositioned in the subject), determining entry points, and/ortrajectories for performing a procedure and/or implantation, and otherselected planning features. Further, the planning can includedetermining placement of a selected implant, such as a lead electrodefor a cardiac system (e.g., a cardiac synchronization system) or a leadfor a brain stimulation system. Accordingly, it is understood that theimage data newly acquired for performing a procedure in soft tissueand/or hard tissue. Various procedures may also require performing aprocedure in both hard and soft tissue.

The system and method disclosed herein can then be used to assist inverifying the selected plan and/or determining a final position of animplant. Various predetermined models of an implant along with trackedinformation of an implant can be used to assist in analyzingintra-procedure or post-procedure image data to determine a finalposition of an implant. Further, the system, in particular withnavigation or testing images can be used to determine positioning of animaging system for acquiring image data of the subject after acquiringthe initial image data, such as the image data acquired procedurally.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

A system and/or method is disclosed that can be used to confirm ordetermine a position of an implant. During a procedure, such as asurgical procedure, an implant or member can be placed in a subject.After a certain time during the procedure or after the procedure iscomplete (e.g. an implant or part of an implant system are placed), animage can be acquired of the subject. A pre-formed model (such as acomputer aided or assisted design (CAD) model) can be overlayed orsuperimposed on the acquired image data at the determined location ofthe implanted member to assist in confirming placement of the implant.The overlayed image can be used to confirm completion of a plannedprocedure as well.

An imaging system can be used to acquire images of the subject, such asa human patient, before the initiation of the procedure, during theprocedure, and after completion of at least a portion of the procedure.Images acquired of a subject prior to initiating a procedure may be usedto assist in planning the procedure, such as selecting a trajectory forthe procedure and selecting an implant. Images acquired during aprocedure may include those acquired after an initial incision and/orpartial placement of an implant and images acquired to assure that theprocedure is progressing according to a pre-determined plan. Theprocedure can include implantation of an implant including an insertionof an implant through an incision and forming an incision.

Images may also be acquired after the procedure is complete to confirmappropriate or selected placement of the implant. The after procedureimages may be used to confirm that a procedure has been completed, asplanned prior to beginning the procedure. The planned procedure may bebased on the initial image data. Further, the after procedure images maybe used by a user to determine if further procedure steps are useful ornecessary.

It is understood by one skilled in the art that implants may includeboney implants, soft tissue implants, or the like. Boney implants mayinclude implants such as medical screws or joint replacement portions.Soft tissue implants may include stents or placements of leads, such ascardiac pacing leads or deep brain stimulation leads. Further,procedures may include ablation procedures or soft tissue resectionprocedures.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is an environmental view of an operating theatre including anoptional imaging system and a navigation system;

FIG. 2 is a flow chart illustrating a procedure for performing andconfirming placement of an implant in a patient;

FIGS. 3-5 illustrate image data of a spine of a patient from variousperspectives;

FIG. 6 is a schematic illustration of an instrument for inserting animplant into a patient;

FIG. 7 is a view of a display with image data and an icon of an implantsuperimposed on the image data;

FIG. 8 is a schematic view of the imaging device in various positionsrelative to a patient;

FIG. 9 is a schematic representation of images based on image dataacquired at the various positions illustrated in FIG. 8 ; and

FIG. 10 is a screen shot of an illustrated position of an implant basedon image data.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

FIG. 1 is a diagram illustrating an overview of a navigation system 10that can be used for various procedures. The navigation system 10 can beused to track the location of an item, such as an implant or aninstrument (as discussed herein), relative to a subject, such as apatient 14. It should further be noted that the navigation system 10 maybe used to navigate any type of instrument, implant, or delivery system,including: guide wires, arthroscopic systems, orthopedic implants,spinal implants, deep brain stimulation (DBS) leads, cardiac pacingleads, ablation instruments, etc. Moreover, the instruments may be usedto navigate or map any region of the body. The navigation system and thevarious tracked items may be used in any appropriate procedure, such asone that is generally minimally invasive or an open procedure.

The navigation system 10 can interface with an imaging system 12 that isused to acquire pre-operative, intra-operative, or post-operative, orreal-time image data of the patient 14. It will be understood by oneskilled in the art, any appropriate subject can be imaged and anyappropriate procedure may be performed relative to the subject. Thesubject may be a human patient and the procedure may be a surgicalprocedure, such as an implantation of a device (e.g. a screw, lead,etc.).

Exemplarily illustrated in FIG. 1 , the imaging system 12 comprises anO-arm® imaging device sold by Medtronic Navigation, Inc. having a placeof business in Louisville, Colorado, USA. The imaging device 12 may havea generally annular gantry housing 20 that encloses an image capturingportion 22. The image capturing portion 22 may include an x-ray sourceor emission portion 26 and an x-ray receiving or image receiving portion28 located generally or as practically possible 180 degrees from eachother within the gantry housing In various embodiments, the x-ray sourceor emission portion 26 and the x-ray receiving or image receivingportion 28 may be mounted on a rotor (not illustrated) relative to atrack (not illustrated) within the generally annular gantry housing 20.The image capturing portion 22 can be operable to rotate 360 degreesduring image acquisition. The image capturing portion 22 may rotatearound a central point or axis, allowing image data of the patient 14 tobe acquired from multiple directions or in multiple planes. The imagingsystem 12 can include those disclosed in U.S. Pat. Nos. 7,188,998;7,108,421; 7,106,825; 7,001,045; and 6,940,941; all of which areincorporated herein by reference. The imaging system 12, however, mayalso include or be replaced with other imaging systems including C-armfluoroscopic imaging systems, computer tomography (CT) imaging systems,etc. which can also generate three-dimensional views of the patient 14.

The position of the image capturing portion 22 can be precisely knownrelative to any other portion of the imaging device 12. In addition, asdiscussed herein, the precise knowledge of the position of the imagecapturing portion 22 can be used in conjunction with a tracking system29 to determine the position of the image capturing portion 22 and theimage data relative to the subject, such as the patient 14, which istracked. For example a patient tracking device 48 may be placed on thepatient 14 to track the patient 14.

The tracking system 29 can include various portions that are associatedor included with the navigation system 10. The tracking system 29 canalso include a plurality of types of tracking systems including anoptical tracking system that includes an optical localizer 40 and/or anelectromagnetic (EM) tracking system that can include an EM localizer42. The optical localizer 40 may “view” or optically track trackableportions (tracking devices) with cameras. The EM localizer 42 maygenerate a field and a trackable portion (e.g. EM tracking device) maysense the field to determination a location relative to another trackingdevice in the field. Various tracking devices, including those discussedfurther herein, can be tracked with the tracking system 29 and theinformation can be used by the navigation system 10 to allow for adisplay of a position of an item. Briefly, tracking devices, such as apatient tracking device 48, an imaging device tracking device 50, and aninstrument tracking device 52, allow selected portions of an operatingtheater to be tracked relative to one another with the appropriatetracking system 29, including the optical localizer 40 and/or the EMlocalizer 42.

It will be understood that any of the tracking devices 48-52 can beoptical or EM tracking devices, or both, depending upon the trackinglocalizer used to track the respective tracking devices. It will befurther understood that any appropriate tracking system can be used withthe navigation system 10. Alterative tracking systems can include radartracking systems, acoustic tracking systems, ultrasound trackingsystems, and the like.

An exemplarily EM tracking system can include the STEALTHSTATION® AXIEM™Navigation System, sold by Medtronic Navigation, Inc. having a place ofbusiness in Louisville, Colorado. Exemplary tracking systems are alsodisclosed in U.S. Pat. No. 8,644,907, issued Feb. 4, 23012, titled“Method And Apparatus For Surgical Navigation”; U.S. Pat. No. 7,751,865,titled “Method And Apparatus For Surgical Navigation”, issued Jul. 6,2010; U.S. Pat. No. 5,913,820, titled “Position Location System,” issuedJun. 22, 1999 and U.S. Pat. No. 5,592,939, titled “Method and System forNavigating a Catheter Probe,” issued Jan. 14, 1997, all incorporated byreference herein.

Further, for EM tracking systems it may be necessary to provideshielding or distortion compensation systems to shield or compensate fordistortions in the EM field generated by the EM localizer 42. Exemplaryshielding systems include those in U.S. Pat. No. 7,797,032, titled“Method and system for navigating a catheter probe in the presence offield-influencing objects”, issued on Sep. 14, 2010 and U.S. Pat. No.6,747,539, titled “Patient-shielding and coil system”, issued on Jul. 8,2004, all of which are incorporated herein by reference. Distortioncompensation systems can include those disclosed in U.S. Pat. No.6,636,757, titled “Method and apparatus for electromagnetic navigationof a surgical probe near a metal object”, issued on Oct. 21, 2003, allof which are incorporated herein by reference.

With an EM tracking system, the EM localizer 42 and the various trackingdevices can communicate through an EM controller 44. The EM controllercan include various amplifiers, filters, electrical isolation, and othersystems. The EM controller 44 can also control the coils of thelocalizer 42 to either emit or receive an EM field for tracking. Awireless communications channel, however, such as that disclosed in U.S.Pat. No. 6,474,341, entitled “Surgical Communication Power System,”issued Nov. 5, 2002, herein incorporated by reference, can be used asopposed to being coupled directly to the EM controller 44.

It will be understood that the tracking system may also be or includeany appropriate tracking system, including a STEALTHSTATION® TRIA®,TREON®, and/or S7™ Navigation System having an optical localizer,similar to the optical localizer 40, sold by Medtronic Navigation, Inc.having a place of business in Louisville, Colorado. Optical trackingsystems may also include those discloses in U.S. Pat. No. 8,010,177,Aug. 30, 2011, Intraoperative Image Registration“; U.S. Pat. No.6,235,038, issued on May 22, 2001, titled “System For Translation OfElectromagnetic And Optical Localization Systems”, all incorporatedherein by reference. Further alternative tracking systems are disclosedin U.S. Pat. No. 5,983,126, to Wittkampf et al. titled “CatheterLocation System and Method,” issued Nov. 9, 1999, which is herebyincorporated by reference. Other tracking systems include an acoustic,radiation, radar, etc. tracking or navigation systems.

The imaging system 12 can include a support housing or cart 56. Theimaging system 12 can further include a separate image processing unit58 that can be housed in the cart 56. The navigation system 10 caninclude the navigation processing unit 60 that can communicate orinclude a navigation memory 62. The navigation member 62 may include anyappropriate non-transitory memory including a random access memory,magnetic media drive, etc. Further, the navigation memory 62 may beintegrated with the navigation processing unit 60 or remote from thenavigation processing unit 60. The navigation processing unit 60 canreceive information, including image data, from the imaging system 12and tracking information from the tracking systems 29, including therespective tracking devices 48-52 and the localizers 40-42. Image datacan be displayed as an image 64 on a display device 66 of a workstationor other computer system 68. The workstation 68 can include appropriateinput devices, such as a keyboard 70. It will be understood that otherappropriate input devices can be included, such as a mouse, a foot pedalor the like. The various processing units and computers or workstationsmay include internal or local memory and processing units. Theprocessing units may include central processing units that are generalcomputers that execute instructions to perform tasks on a chip. Theprocessing units may also be specific circuits, such as applicationspecific integrated circuits (ASIC). Accordingly, the processing unitsmay be devices that receive information and execute instructions thatare stored or received based on the information.

The image processing unit 58 processes image data from the imagingsystem 12 and transmits it to the navigation processing unit 60. It willbe further understood, however, that the imaging system 12 need notperform any image processing and it can transmit the image data directlyto the navigation processing unit 60. Accordingly, the navigation system10 may include or operate with a single or multiple processing centersor units that can access single or multiple memory systems based uponsystem design.

The patient 14 can be fixed onto an operating table 72, but is notrequired to be fixed to the table 72. The table 72 can include aplurality of straps 74. The straps 74 can be secured around the patient14 to fix the patient 14 relative to the table 72. Various apparatusesmay be used to position the patient 14 in a static position on theoperating table 72. Examples of such patient positioning devices are setforth in commonly assigned U.S. patent application Ser. No. 10/405,068,published as U.S. Pat. App. Pub. No. 2004/0199072, entitled “AnIntegrated Electromagnetic Navigation And Patient Positioning Device”,filed Apr. 1, 2003, which is hereby incorporated by reference. Otherknown apparatuses may include a Mayfield® clamp.

Also, the position (including three-dimensional location andorientation) of the patient 14 relative to the imaging system 12 can bedetermined by the navigation system 10 with the patient tracking device48 and the imaging system tracking device 50. As discussed herein, theposition (including three-dimensional location and orientation) relativeto the patient 14 may be determined, at least in part, with imagesacquired of the patient 14. Accordingly, the position (includingthree-dimensional location and orientation) of the patient 14 relativeto the imaging system 12 can be determined. The imaging system 12, suchas the O-arm® can know its position and be repositioned to the sameposition within about 10 microns. This allows for a substantiallyprecise placement of the imaging system 12 and precise determination ofthe position of the imaging device 12. Precise positioning of theimaging portion 22 is further described in U.S. Pat. Nos. 7,188,998;7,108,421; 7,106,825; 7,001,045; and 6,940,941; all of which areincorporated herein by reference. Generally, it may be selected todetermine the position of the image data relative to the patient 14. Forexample, the position, including the orientation relative to thepatient, of the image data may be used to determine a location of aportion of the patient 14.

Subject or patient space and image space can be registered byidentifying matching points or fiducial points in the patient space andrelated or identical points in the image space. The imaging device 12,such as the O-arm® imaging device sold by Medtronic, Inc., can be usedto generate image data at a precise and known position. This can allowimage data that is automatically or “inherently registered” to thepatient 14 upon acquisition of the image data. Essentially, the positionof the patient 14 is known precisely relative to the imaging system 12due to the accurate positioning of the imaging system 12 relative to thepatient 14. This allows points in the image data to be known relative topoints of the patient 14 because of the known precise location of theimaging system 12.

Alternatively, manual or automatic registration can occur by matchingfiducial points in image data with fiducial points on the patient 14.Registration of image space to patient space allows for the generationof a translation map between the patient space and the image space.According to various embodiments, registration can occur by determiningpoints that are substantially identical in the image space and thepatient space. The identical points can include anatomical fiducialpoints or implanted fiducial points. Exemplary registration techniquesare disclosed in Ser. No. 12/400,273, filed on Mar. 9, 2009, nowpublished U.S. Pat. App. Pub. No. 2010/0228117, incorporated herein byreference.

Once registered, the navigation system 10 with or including the imagingsystem 12, can be used to perform selected procedures. Selectedprocedures can use the image data generated or acquired with the imagingsystem 12. Further, the imaging system 12 can be used to acquire imagedata at different times relative to a procedure. As discussed herein,image data can be acquired of the patient 14 subsequent to a selectedportion of a procedure for various purposes, including confirmation ofthe portion of the procedure.

With continuing reference to FIG. 1 , the imaging system 12 can generateactual or virtual three dimensional images of the patient 14. Thepatient 14 can be placed relative to the imaging system 12 to allow theimaging system 12 to obtain image data of the patient 14. To generate 3Dimage data, the image data can be acquired from a plurality of views orpositions relative to the patient 14. The 3D image data of the patient14 can be used alone or with other information to assist in performing aprocedure on the patient 14 or an appropriate subject. It will beunderstood, however, that any appropriate imaging system can be used,including magnetic resonance imaging, computed tomography, fluoroscopy,etc. to acquire image data (including 3D image data) of the patient 14.

With initial reference to FIG. 2 , a flow chart 100 illustrates a methodfor confirming placement of an implant after an implantation procedure,as illustrated in FIGS. 3-10 . It will be understood that although theflowchart 100 describes and is directed to a method of placing a spinalimplant, including one or more pedicle screws 120 in a vertebra 124. Themethod 100, however, may be used to acquire image data to assist inconfirming placement of any appropriate implant in any appropriateportion of the anatomy, such as an intramedullary (IM) rod in a longbone (e.g. a femur), a knee or hip replacement prosthesis, or any otherappropriate procedure. Accordingly, the method in flowchart 100 will beunderstood to encompass selected procedures beyond pedicle screwplacement. In addition, it will be understood that the method of theflowchart 100 can be used to confirm placement of any appropriate memberin any appropriate structure. For example, placement of a member,including a spike, into a radiolucent work piece (e.g. wood board), canalso be confirmed with the method in the flowchart 100.

The method in the flowchart 100 can begin at start block 102. Aprocedure can then be selected in block 104. The procedure can be anyappropriate procedure, such as the placement of the pedicle screw withinthe vertebra 124 (FIG. 6 ) of a patient 14. It will be understood thatthe placement of the pedicle screw 120 in the vertebra 124 of thepatient 14 can be performed for any appropriate procedure, such asspinal fusion or vertebral rigidity. Regardless of the procedureselected in block 104, a first image data of the subject 14 can beacquired in block 106. The first image data may be acquired, however,prior to the determination of a procedure to be performed. For example,the first image data acquired in block 106 may be initial diagnosticimage data that is used to select, confirm, and/or plan the procedure inblock 104. The first image data, therefore, may be pre-procedure orpre-acquired image data. The first image data is image data of thepatient 14 prior to performing the selected procedure from block 104.

In selecting the procedure to be performed in block 104, a surgical planmay be generated, as understood by one skilled in the art. The surgicalplan may include selection of entry positions, trajectories forimplantation of implants (e.g. pedicle screws), selection of instrumentsfor performing the procedure, and other appropriate selections and stepsfor the procedure. The procedure, however, need not be a surgicalprocedure and may include a plan for carrying out other selectedprocedures, such as installing or assembling a mechanical assembly (e.g.an automobile).

The image data acquired in block 106 can be any appropriate image data,such as x-ray image data of a single vertebra, illustrated in FIG. 3 ,in a superior viewpoint. The image data may also include an image of aplurality of vertebrae, as illustrated in FIG. 4 , from a lateralperspective. Further, the image data may include a posterior perspectiveof a plurality of vertebrae, as illustrated in FIG. 5 . The image datacan be displayed on the display 66 as the image 64 a, 64 b, 64 c,respectively, or can be acquired and saved in the memory or storagesystem 62 of the navigation system 10, can be used for laterconfirmation of a procedure, or can be used for both.

Briefly, a first image data of the subject can be image data acquired ofthe subject or the patient 14 prior to any portion of a surgicalintervention being performed. For example, the patient 14 can be imagedwith the imaging system 12 substantially immediately after entering anoperating theater and prior to performing any surgical procedures, suchas forming an incision. It will be further understood that the firstimage data of the subject acquired in block 106 can be acquired at anypoint prior to the patient 14 entering the surgical theater. Regardlessof the timing of acquiring the first image data, the first image data isimage data of the patient or subject 14 in a first condition, such ashaving been unaltered by a surgical procedure. As discussed furtherherein, in relation to the method in the flowchart 100, this image datacan be used along with later or second acquired image data and a model(e.g. a CAD model) of an implant for confirmation of placement of animplant in the patient 14.

As discussed above, however, the image data acquired in block 106 can beacquired at a selected position relative to the patient 14. Asillustrated in FIG. 1 , the imaging device tracking device 50 can betracked as can the patient 14 with the patient tracker 48. Thus, theposition of the imaging device 12 relative to the patient 14 can bedetermined with the navigation system when acquiring the first imagedata in block 106. This first imaging position may be saved in block109. This first imaging device position saved in block 109 may include adiscrete position (including a location and an orientation) for eachimage portion acquired of the patient 14. For example, a plurality ofexposures may be acquired and each exposure may be at a differentposition relative to the patient 14. Thus, the first imager positionsaved in block 109 may include a position for each exposure of theimaging device 12 acquired with the first image data. These positionsmay be saved for later recall, such as being saved in the navigationmemory 62.

After the first image data is acquired in block 106, the first imagedata can be optionally transferred to a data processor in block 112. Theimage data transferred to the data processor in block 112 can be allfirst image data acquired of the patient 14 in the first image data fromblock 106. The first image data from block 106 may be viewed astwo-dimensional (2D) projections of the subject 14 or may be used togenerate a three-dimensional (3D) model of the subject 14. For example,one of more 2D projections may be processed in block 112 to generate a3D model of the subject 14. The model may then be viewed as the image onthe display. Further, a procedure may be planned with the 3D model andat least a portion of the plan (e.g. selected final implanted locationsof members) may be illustrated as icons superimposed on the 3D modeland/or 2D projections. As illustrated in FIGS. 3-5 , image data can beacquired of the patient 14 from a plurality of perspectives orviewpoints.

The first image data acquired in block 106 can be saved or transferredto any appropriate processing core or system, or can simply be directlytransferred or maintained to be accessed by a single processing unit. Asdiscussed above, the imaging processing unit 58 can be incorporated inthe imaging system 12 and the navigation processor 60 can be includedwith the navigation workstation 68. Accordingly, the two processingunits can communicate and image data can be transferred therebetween.Alternatively, the image data can be simply acquired and transferred tothe navigation processor 60. Regardless, it will be understood that thenavigation system 10 can process the image data with a single ormultiple processing unit or cores as understood by one skilled in theart.

Once the first image data is acquired in block 106 and optionallytransferred to a processor in block 112, the selected procedure can beperformed in block 114. As illustrated in FIG. 6 , the procedure caninclude placement of a pedicle screw 120 into the patient 14. As isgenerally understood, the anatomy of the patient 14 can include thevertebra 124 into which the pedicle screw 120 can be positioned orimplanted. The pedicle screw 120 can be implanted with an appropriatesurgical instrument, such as surgical motor 126 or can be implanted withan appropriate manual driver (not illustrated) such as the CD Horizon®Legacy(™) System manual driver, sold by Medtronic Spine and Biologicshaving a place of business in Minneapolis, MN. Regardless of theinstrument used to implant the pedicle screw 120, the instrument and/orthe pedicle screw 120 can include a tracking device 52. The trackingdevice 52 can be tracked by the navigation system 10, such as witheither or both of the tracking systems including the optical localizer40 or the EM localizer 42 during the surgical procedure.

The tracking device 52 allows the navigation system 10 to determine andillustrate a position of the pedicle screw 120, the implantationinstrument 126, or combinations thereof relative to image data acquiredof the patient 14. For example, as illustrated in FIG. 7 , one or moreicons 120 i can be superimposed on the first acquired image data 64 a,b, c of the patient 14 as the one or more of the pedicle screws 120 ismoved towards the vertebra 124 of the patient 14. As discussed above,one or more of the pedicle screws 120, or other appropriate implantmembers, may be tracked into the patient 14. Further, the instrument oritem tracked need not be an implant or a hard tissue implant, but mayinclude a soft tissue implant (e.g. DBS lead). The determined positionof the pedicel screw 120 at any appropriate time, such as during orafter implantation, may be saved into the navigation memory 62 or otherappropriate memory system for later recall. The determined and/or savedposition of the pedicle screw 120 may then be used, as discussed herein,for confirmation of the selected procedure or plan for the selected(e.g. surgical) procedure.

As illustrated in FIG. 6 , as the pedicle screw 120 moves towards andinto the vertebra 124, the icon 120 i (in FIG. 7 ) can be illustratedrelative to the image 66. It is understood by one skilled in the art,FIG. 6 illustrates a single one of the pedicle screws 120 prior toinsertion into the vertebra 124, while FIG. 7 illustrates two icons 120i to illustrate two individual pedicle screws placed into an image 124′of the single vertebra 124.

The icon 120 i can be a preformed model (such as a computer aideddrafting figure) of the screw including a priori precise dimensioninformation of the implant, such as the pedicle screw 120. The preformedmodel can be stored in the navigation memory device 62 and can beaccessed by an appropriate processor, such as the navigation processor60. It is understood, however, that the dimensions of the implant can bedetermined during the procedure, such as by measuring or using atrackable calibration instrument. The dimensions may then be input tothe navigation system 10. It will be further understood, however, thatnavigation is not required for the performing of the procedure. Forexample, a low invasive or open procedure may be used to place theimplant with no navigational assistance. It will also be understood thatthe image data 64 a of the vertebra can include other information suchas a centerline icon 140 that can be automatically or manuallydetermined relative to the image data 64 a.

The navigation system 10, by the tracking of the pedicle screw 120either directly or through a navigated instrument, can be used toillustrate a determined position (including location and orientation) ofthe pedicle screw 120 relative to the vertebra 124. By illustrating theicon 120 i superimposed on the image data 64 a,b,c of the patient 14,the user 54 can guide or be given feedback regarding the position of thepedicle screw 120 relative to the patient 14 and the vertebra 124.Accordingly, at a selected time, the user can select to stop driving thepedicle screw 120 into the patient's 14 vertebra 124 based upon theposition of the icon 120 i or other appropriate information. Later, thetracked icon 120′ may be removed when the pedicle screw 120 is notdirectly tracked by the tracking system or navigation system 10. Theposition of the pedicle screw 120 may be determined directly based onimage data, as discussed herein.

Generally, the imaging system 12 is moved from a position relative tothe patient 14 after acquiring the first image data in block 106 andperforming the procedure in block 114. For example, the imaging device12 is moved to allow access to the vertebra 124 for implantation of thepedicle screw 120. The imaging device 12, however, may be moved for anyother appropriate reason. As a further example, the imaging device 12may be moved to allow greater access to a cranium for a DBS placement.It is understood, however, that even when the imaging system 12 is movedthat the location of the pedicle screw 120 or other member may be savedwithin the navigated space. For example, the position of the screw 120relative to the patient tracker 48 may be saved for recall by thenavigation processing unit, or other appropriate processing unit. Theposition of the pedicle screw 120, for example, may be saved after aselected period of time, such as after implantation or prior toacquiring second image data. The saved position of the pedicle screw 120may then be recalled to, for example, positon the imaging system 12 toacquire the second image data.

Nevertheless, if a second image data is to be obtained the imagingdevice 12 may be needed to be moved relative to the patient 14. Forexample, if the imaging device 12 no longer surrounds a portion of thepatient's 14 spine, then the imaging device may be moved back tosurround a portion of the spine. It may be selected and/or desirable,however, to minimize radiation to which the patient 14 is exposed. Asthe second image data is generally acquired to confirm a plannedprocedure, a full 360 exposure to the patient 14 may not be necessary.Thus, as discussed herein the imaging device 12 may be moved relative tothe patient 14 to acquire image data that results in less exposure tothe patient 14 than the first image data acquired in block 106. Forexample, a determination, such as with the imager processing unit 58and/or the navigation processing unit 60

Thus, once the user 54 determines to stop driving the pedicle screw 120into the vertebra 124, a determination is made of whether a second imagedata of the subject 14 can be acquired in block 150. The second imagedata acquired of the patient 14 can be image data that is acquired withthe imaging system 12, or any appropriate imaging system, of the patient14 after the pedicle screw 120 is positioned within the vertebra 124 toa selected amount or distance.

The second image data may be illustrated, as discussed herein, for useby the user 54. The second image data may also be augmented with variousinformation, such as a model of the implant. For example, second imagedata may have a model of an implant that is superimposed thereon basedon tracking information, as disclosed in U.S. Pat. No. 8,842,893, issuedon Sep. 23, 2013, titled “Method and Apparatus For Image-BasedNavigation”, incorporated herein by reference. As discussed above, themodel of the implant may be used to assist in navigation. Further,selected measurements of the implant may be acquired. Nevertheless, theimage data of the patient 14 may be used to assist in performing and/orconfirming the procedure being performed on the patient 14.

With continuing reference to FIG. 2 the determination of whether toacquire second image data in block 150 may be for various purposesincluding confirming a procedure, determining a current location of animplant (e.g. the position of the pedicle screw 120), determiningfurther procedure steps, or for other appropriate reasons. As anexample, in the following discussion, it may be selected to confirm thatthe implant 120 has reached or been positioned in a planned positioninto the vertebrae 124. However, if it is desired or determined thatconfirmation image data is not needed, a NO path through block 152 maybe followed and the process may END in block 154. For example, if anopen procedure is performed, a confirmation image may not be selected ornecessary at a selected time. Further, other confirmation techniques maybe employed that do not include acquiring second image data of thesubject 14.

Nevertheless, a second image data may be selected in the block 150 and aYES path can be followed through YES block 160. The determination inblock 150 may be automatically or by input of a user. For example, theprocedure may be included as a program that is executed by thenavigation processing unit 60 and a prompt for second image data may begiven.

After the YES block 160 is determined, however, from block 150, adetermination block of whether the patient tracker 48 is attached to thepatient 14 in block 162 may be determined. The determination of whetherthe patient tracker is still attached in block 162 may also be manual orautomatic. For example, the user 54 may input to the system, such asusing the keyboard that the patient tracker is attached. Further, oralternatively thereto, the system, such as including the tracking system29 and the navigation system 10, can determine whether a signal isreceived or being measured from the patient tracker 48 attached to thepatient 14. If the patient tracker 48 is determined to still beattached, then a yes path is followed through YES block 163. Thetracking system 29 and navigation system 10 can track the patient 14 andthe imaging system 12 such as with the imaging system tracking device50. When tracking, the navigation system 10 may then determine theposition of the patient 14 and the imaging system 12 for variouspurposes, such as acquiring additional image data, includingconfirmation image data. Further, as discussed above, the position ofthe implant, for example the pedicle screw 120, may have been determinedby tracking the position of the pedicle screw 120 such as with theinstrument tracker 52 during the procedure. The position of the implant120, therefore, may be known and recalled from the navigation memory 62.The saved position of the pedicle screw may be from when the pediclescrew 120 was tracked during implantation and the position of thepedicle screw 120 was saved into the navigation memory 62.

As illustrated in FIG. 1 , the imaging device 12 can be positionedrelative to the patient 14 to acquire the first image data in block 106.However, in performing a procedure, such as placing the pedicle screw120, the imaging device 12 may be moved away from the patient 14. Ifmoved away from the patient 14, the patient 14 is repositioned relativeto the imaging device 12 for acquiring second image data. Generally, theimaging device 12 may be moved near the patient 14 or the patient 14 maybe moved near the imaging device 12. During movement the exactpositioning of the imaging device 12 relative to the patient 14 may havechanged from when the first image data was acquired.

A three dimensional model of the patient 14, or at least a portion ofinterest or anatomy of interest of the patient 14, may be produced forviewing on the display 66 from the first image data. The first imagedata, therefore, may require many projections (e.g. about 300 to about700 projections, generally each acquired at different positions) throughthe patient 14 to acquire sufficient image data to generate thethree-dimensional model of the patient 14. When acquiring the secondimage data, however, it may not be necessary or selected to acquire asmany projections as during acquiring the first image data. The secondimage data may be selected for verification or confirmation of implantplacement, and model creation, thus less image data may be necessary.Thus, acquiring minimal projections through the patient 14 can minimizeor reduce the amount of radiation experienced by the patient 14 and theuser 54.

The second image data, therefore, may include selecting a selectednumber or minimal projections through the patient 14 may be made. Thesecond image data may also be referred to as confirmation orverification image data. Thus, determining appropriate or best positionsof the imaging device to acquire the second image data may assist inminimizing the number of projections or views needed. Each projectionmay require an exposure to radiation, such as x-ray radiation to acquireimage data of the subject 14. In particular, the imaging device 12 maybe operated to acquire views in the second image data to determine theposition of the implanted member, such as the pedicle screw 120, with aselected number, such as a small number including two, projectionsthrough the patient 14. The determined position of the implant from theacquired second image data can be used to generate an icon forsuperimposing on the first acquired image data or model generatedtherefrom, as discussed herein.

By maintaining tracking of the patient 14 with the patient trackingdevice 48, the imaging device 12 can be tracked with the tracking deviceto position the imaging device 12 relative to the patient 14 to acquirethe minimal or selected number of projections while acquiring enoughimage data to appropriately view the implant 120. For example, in block164 a recall of the position of the imaging device during acquisition ofthe first image data from block 106 may occur.

The recalled position of the imaging device from block 164 may assist ina determining one or more positions of the imaging device for acquiringthe second image data in a block 165. In particular, a relative positionof the imaging device 12 and the patient 14 may be determined foracquiring the second image data. The relative position may be based onthe recalled position for acquiring the first image data from block 164.Further, in determining relative positions for acquiring the secondimage data in block 165, the recalled position of the implant member,such as the pedicel screw 120 may also be made. The tracked position ofthe pedicle screw 120 may be used to assist in determining appropriateor optimal positions for acquiring the second image data. As discussedherein, optimal positions of the imaging device for acquiring the secondimage data may be imaging as many views and/or as much of the implanteddevices as possible in each view. Further, the optimal positions mayinclude minimizing or reducing overlap of multiple implants in a singleview and/or overlap of selected anatomical features or structures. Thismay allow for a minimal number of views for confirmation of the positonof the pedicle screw 120, or other implant, according to the plan and/orselected procedure from block 104. Thus, at least because the implant istracked and the implant's location relative to the patient 14 is known,a position for the imaging device to acquire image data of the implantcan be determined.

The determination of the positions in block 165 may be determined withthe processing unit, including the navigation processing unit 60, byexecuting instructions to determine selected positions of the imagingdevice to acquire the second image data. The determined position of theimaging device may be to ensure imaging of at least more than oneimplant in each view or projection when acquiring the second image data.Thus, an implant may be unobstructed by a second implant in the acquiredsecond image data. Further, the determined relative positions mayinclude positioning the imaging device 12 according to any of thepossible positions of the imaging device 12 including, rotation, sway,wag, axial movement, and transverse movement relative to a long axis ofthe subject 14.

Therefore, if the YES path 163 is followed the imaging device 12 can bemoved and/or tracked in block 166. Also the patient can be moved and/ortracked in block 168. While tracking the patient in block 168 andtracking the imaging device in block 166, the imaging device can bemoved to one or more selected positions, which may allow for acquiringimage data at one or more perspectives or views, relative to the patient14 in block 170. The positions may be determined in block 165 and thepatient and/or imaging device may be moved in block 170.

With continuing reference to FIG. 2 and additional reference to FIGS. 8and 9 , the imaging device 12 that includes the source 26 and thedetector 28 can be moved relative to the patient 14 including thevertebrae 124. The imaging device 12 may be moved to acquire selectedimages for the second image data. The second image data may be optimalor procedurally optimal positions of the imaging device 12 to acquirethe second image date with a minimal number or selected number ofprojections. The selected number may be a number appropriate or adequatefor a confirmation of the selected and planned procedure. The selectedand planned procedure may be a selected location for implantation of thepedicle screw 120.

FIG. 8 schematically illustrates the source 26 in various locations 26′,26″, and 26′″ relative to the detector in various locations 28′, 28″,and 28′″. Further the imaging device tracking device 50 is illustratedin various positions 50′, 50″ and 50′″. The tracking device locations50′, 50″, 50′″ can be used to track and determine location of the sourceat the various locations 26′, 26″ and 26′″ and/or the detector atvarious locations 28′, 28″, and 28 ″ for generating views relative tothe vertebrae 124. The source 26 can emit x-rays through the patient 14to create image data at the detector 28, as is generally understood inthe art. Each of the projections can create a view as illustrated asview A, view B, and view C in FIG. 9 relative to the position of thesource 26′, 26″ and 26′″, respectively illustrated in FIG. 8 .

As noted above, in block 165 the navigation system 10 can be used toautomatically determine the positions of the source 26 relative to thepatient 14 to acquire views that would acquire image data of all of theimplants positioned and their relative locations to each other.Therefore, in block 176 acquire second image data at a selected numberof positions of the imaging system 12 occurs. The views may refer to orbe at positions that are determined in block 165. The views can includeacquiring one or more views or projections for illustrating ordetermining the position of the implant relative to the subject 14.Thus, the second image data may include a plurality of views from aplurality of positions of the imaging device 12. For example, two ormore views may be acquired of the subject 14 for the second image data.

With continuing reference to FIG. 2 and reference to FIGS. 8 and 9 , atView A the source 26′ can be tracked with the image tracking device 50′and x-rays can be projected through the vertebrae 124 to the detector28′. The image data acquired can be displayed or saved and can include aview 180 that illustrates or includes image data of a first pediclescrew 120 a and the second pedicle screw 120 b. Specifically the imageof View A can include an image 120 a′ of the first pedicle screw and animage 120 b′ of the second screw. As both of these screws 120 a, 120 bcan be viewed in the View A 180 a determination of geometry and positionof the screws may be collected from View A.

Additionally, the imaging device 12 can be operated to move the sourceto source position 26″ by tracking the tracking device 50″. For example,the navigation processing unit 60 can be used to provide coordinates forpositioning the imaging device 12 and/or directly control the imagingdevice 12. Regardless, a projection of x-rays can then be made throughthe vertebrae 124 and the two screws 120 a, 120 b may be imaged at thedetector at the position 28″. View B 184 can also include image data ofthe two screws 120 a, 120 b in a different perspective, as imaged at 120a″ and 120 b″, from the View A 180. The two views 180, 184 can be usedto create a calculation of a position of the two screws 120 a, 120 b,relative to the vertebrae 124 which is also included in the image dataas vertebra image 124′ and 124″. It is understood, as discussed above,that movements of the detector 28 and/or source 26 may include more thanrotational movement and may also include linear movements along ortransverse to a long axis of the subject 14.

As illustrated in FIG. 9 the images 180, 184 include image data of bothof the implanted pedicle screws 120 a, 120 b and show them in varyingperspectives. Therefore, appropriate algorithms may be executed with thenavigation processing unit 60, or other appropriate processing unit, todetermine a position of the screws relative to the anatomy, includingthe vertebra 124. In addition, the geometrical configurations and sizesof the screws 120 a, 120 b can be stored in the navigation memory 62 andrecalled to assist in determining the position of the screws 120 b and120 a in the vertebrae 124.

A determination of a position the implant in the second image data ismade in block 182. The determination may be made with one or moreprocessing units, such as the imaging processing unit 58 or thenavigation processing unit 60. The selected processing unit may executeselected instructions to determine the position of the members withinthe second image data in block 182.

The determination or identification of the implant, such as the pediclescrew 120 in the second image data may include various processing steps.For example, a user may identify a seed point in one or more of theviews or projections. Further, the pedicle screw may include a selectedpixel or voxel contrast or brightness. In either situation, variousregion growing techniques may be used to segment the pedicle screw 120from the image. Thus, the process may include segmenting the image datafrom a selected seed point.

The seed point may also be determined (i.e. automatically determined byexecuting instructions with a processor) or selected based on the knownor recalled determined implanted position. As discussed above, thepedicle screw 120 may be tracked as it is implanted and the implantedposition may be saved. The saved position may be recalled in block 164or block 165 by a processor, such as the navigation processor. Therecalled position may also, therefore, be used in determining a locationof the pedicle screw 120 for segmentation from the image data acquiredat the second image data or a portion of the second image data (such asa single view). The recalled position of the pedicle screw 120 may beused to determine a selected point, such as a point at a center of thepedicle screw 120. In various embodiments, the processor that recallsthe saved position may use the saved position to determine a seed pointin the image data. The geometry of the pedicle screw 120 may also bestored in the memory 62 and recalled. Thus, segmentation anddetermination of the position of the screw in the image data may beginwith a point at known center of the saved geometry of the pedicle screw120.

Illustrating a position of the implant, including the screws 120 a, 120b, based on the second image data can be performed in block 188. Theposition of the screws 120 may be illustrated on the first image datafrom block 106, a model based on the imager data from block 112, or thesecond image data from block 176. The position of the screws 120 in thefirst image data block 106 or the processed model from block 112 may bebased on the determined position of the screws 120 in block 182.Moreover, the determined position of the member 120 for illustrationsuperimposed on or relative the first image data block 106 or model formblock 112 may be based only on the determination of the position of thescrews in block 182 in the second image data.

In various embodiments, if the screws are to be illustrated on the firstimage data acquired in block 106 or on a model generated with the firstimage data, the second image data acquired in block 176 may be firstregistered to the first image data or the model in block 179. Inregistering the first image data to the second image data, points in oneof the two image data are correlated or mapped to a point in the otherimage data. The second image data may be registered to the first imagedata using various techniques, such as known in the art regardingtwo-dimensional (2D) to three-dimensional (3D) registration techniques.In various embodiments, boney features or structures that may be presentin both the first image data and the second image data may be identified(e.g. manually or automatically) and extracted in both of the first andsecond image data. The extracted features or structures may be matchedand used for registration and mapping. In addition or alternatively, thesecond image data may be registered to the first image data based on therecalled position of the imaging device from block 164. Thus, theposition of the second image data may be known relative to the positionof the first image data and registration may occur.

The position of the pedicle screw 120 may be determined in the secondimage data, as discussed above. Through the registration, the positionof the pedicle screw may then be mapped or determined in the first imagedata. This registration, therefore, may allow the determined position ofthe pedicle screw 120 from the second image data to be placed orillustrated in the first image data and/or the model that is based onthe first image data.

The determined positions of the screws 120 a, 120 b may be ill-used asicons representing the screws can be superimposed at the determinedpositions on the models that may be generated, such as in the processimage data block 112, based on the acquired first image data in block106. The acquired second image data from block 176 need not be used tocreate a new model or may not be viewed directly by the user 54, but maybe used by the imaging processing unit 58 or the navigation processingunit 60 to generate a view, such as with the icons 120 q (FIG. 10 ) forviewing by the user 54 on the models created with the acquired firstimage data from block 106. Based upon the above described, the user 54can view the implanted position of the implant 120 a, 120 b relative tothe acquired first image data, which also may be used to generate aplan.

In other words, the determined position of the pedicle screw 120 (againit is understood by one skilled in the art that any member may beimaged) may be made based upon the second image data acquired in blocks176, 302. According to various embodiments, the position of the pediclescrew 120 may be determined substantially only or only based upon thesecond image data. The determined position may then be displayedrelative to the first image data and/or a model based on the first imagedata. The model may include a 3D model of the selected region of thepatient 14. The 3D model based on the first image data may include a 3Drendering from a plurality of 2D slices or projections or otherappropriate first image data. Regardless, registration of the secondimage data to the first image data may allow a representation of thepedicle screw 120 to be displayed on the first image data or model.Because the second image data follows the procedure, the determinedposition of the pedicle screw 120 in the second image data may be usedas a confirmation of the procedure when the pedicle screw 120 isillustrated on the first image data.

With reference to FIG. 10 , the image 124′ of the vertebra 124 can begenerated using the first acquired image data from block 106. A planicon 120 p can be illustrated relative to the image 124′. The plan iconmay include a planned or selected position for one or more implantsbased on the first acquired image data from block 106. The plan icon 120p may be a precise 2D or 3D model of the selected implant or may only bea geometrical representation of a selected implant. After the secondimage data is acquired in block 176, a confirmation icon 120 q may beillustrated relative to the image 124′ in addition to the plan icons 120p or alternatively thereto. As discussed above, the second image datamay be registered to the first image data to allow the determinedposition of the pedicle screw 120 to be illustrated superimposed on theimage 124′.

Therefore, the user 54 can view the confirmation icons 124 q atpositions determined, at least in part or in whole, by the second imagedata acquired in block 176. In other words, the position of the pediclescrew 120 in the second image data may be based upon analysis of thesecond image data (e.g. based on segmentation of the pedicle screw fromthe second image data). The position of the second image data to thefirst image data may then be used to illustrate the determined positionof the pedicle screw on the first image data. As noted above, theconfirmation icons 120 q may be superimposed on the image data relativeto the plan icons 120 p so that both are superimposed on the image data124′. Therefore, the second image data may be used to illustrateconfirmation icons 120 q relative to the image data 124′ that can beused to generate an initial plan for a procedure.

For reference, with reference to FIGS. 8 and 9 , a View C may begenerated when the source 26 is at source position 26′″ and may betracked with the tracker 50 at tracker position 50′″. At the View Cposition, the source 26 projects x-rays through the vertebra 124 to thedetector position 28′″. The View C 190, illustrated in FIG. 9 , mayinclude a view of only one screw, even though two are present. One ofthe two screws may obscure the other screw. Thus, at least one of thescrews may be obstructed by another screw in the View C. Therefore, ViewC may not provide appropriate information for determining a position ofthe implants, including the screws 120 a, 120 b. In other words, View Cmay be obstructed or obscured (e.g. at least one item of interested,such as one of the pedicle screws, is at least partially obscured orobstructed by another one of the pedicle screws) while View A and Viewmay be unobstructed or unobscured views. The unobstructed views allowfor a determination of all or most of the members with fewerprojections, including radiation exposures, through the patient 14.

Tracking the imaging device 12 with the imaging device tracking device50, thus, may assist in moving the imaging device to effective andefficient positions for acquiring the second image data. Thisdetermination in block 165 may reduce the number of exposures needed toacquire enough image data to make a determination of positions of theimplants. Thus, acquiring the second image data according to the method100 may require a minimal amount of views or projections that include ahigh discrimination of position information of the implants relative tothe vertebrae 124. This can ensure that a less discriminatory view, suchas View C 190, is not or need not be acquired and therefore not exposingthe patient to x-rays when acquiring such a view.

As discussed above, a determination can be made in block 162 whether apatient tracker is still attached to patient 14. If a patient tracker isnot attached, then a no path to NO block 200 may be followed. Theimaging device 12 may still be moved relative to the patient 14 during aprocedure on the patient, such as implantation of the pedicle screws120, and the imaging device 12 may be again moved relative to thepatient 12 to acquire the second image data it is determined to beacquired in block 150. When the patient is no longer tracked with thepatient tracking device 48 at least one test image data projection orview can be acquired of the patient 14 to assist in determiningappropriate positions for the imaging system 12 relative to the patient14 to acquire a minimal number of projections through the patient 14 todetermine the position of the implant, as discussed above.

When following the no path through NO block 200, the imaging device 12can be moved relative to the patient 14 to a imaging device first testposition in block 202. The imaging device test position can be anyappropriate position relative to the patient 14 and may include both apositioning of the gantry 20 and a selected location of the source 26and the detector 28. At the first test position a first test image datamay be acquired in block 204. The first test image data can be an imagedata acquired as a projection taken through the patient 14 at the firsttest position.

The image data acquired at the first test position at block 204 can beprocessed with an appropriate processing unit, such as the imageprocessing unit 58 or the navigation processing system 60, to determinea position of the implants 120 in the acquired first test image data.The determination of the orientation and location of the implants 120 inthe first test image data allows for a determination of one or morepositions for acquiring second image data in block 208. It isunderstood, however, that the first test image data may also be used asa view or projection of the second acquired image data. Further, thedetermination of one or more positions for acquiring second image datain block 208 may be based only on the acquired first test image data inblock 204. Thus, a tracking of the imaging device 12 relative to thepatient 14, including the patient tracker 48, is not necessary to forthe determination of one or more positions for acquiring second imagedata in block 208.

The first test image data may be used to determine positions of theimagining device to acquire second image data. Thus, rather thantracking the imaging device 12, as discussed above, the first test imagedata may be analyzed to determine appropriate positions for acquiringthe second image data. In the determine positions for acquiring thesecond image data in block 208, the first test image data may beevaluated to determine the positions of the implants therein andrelative to the patient 14. The first test image data, however, may notinclude enough image data to fully determine positions of all of theimplants 120. Thus, the determined positions in block 208 may allow foracquiring the second image data with the imagining device 12 at aminimum number of positions to acquire a minimum number of projectionsto determine the position of the implants, as discussed above.

Analyzing the first test image data can be done in a manner similar toprocessing the image data to generate a model, as is generallyunderstood in the art, and allows for determining the position of theimplants in the first test image data. Therefore, the determination ofthe location for acquiring the second image data in block 208 can beperformed without tracking the patient 14 with the patient tracker 48 ortracking the imaging device 12 with the imaging device tracking device50. As the location and orientation of the implant 120 is determined inthe first test image data, the determination of location for acquiringsecond image data can be based thereon.

Further, procedure information may also be input automatically or by theuser or recalled from the plan that is saved in the memory 62. Forexample, a number of implants and selected relative position of theimplants may be used to assist in determining positions in block 208.For example, if a first test image includes only two implants, but it isknown that four implants were placed, the processor may determine arelative position of the two implants in the image to determine a likelyposition of the other two implants. Further, if an axial view imagedonly two implants, a selected oblique view may be selected to image allfour of the implants. The determining of the positions of the imagingdevice may be automatically determined by the processor based on therecalled information and analysis of the first test image data. Further,the positions of the implants may be recalled by the processor systemform the memory system.

Once the determination for location of acquiring the second image datain block 208 is completed, the imaging device 12 can be moved to thedetermined one or more positions relative to the subject in block 300.Second image data can then be acquired at the one or more positions inblock 302 in a manner similar to acquiring second image data in block176. Once the second image data is acquired at the determined one ormore positions in block 302 the position of the pedicle screws 120 maybe determined in the second image data in block 182, as discussed above(e.g. by segmentation of the pedicle screws form the second image data).The second image data may also be registered to the first image data inblock 179, as also discussed above. In various embodiments, registrationmay occur by feature or structure extraction and registration betweenthe first and second image data. The determined position of the pediclescrews can be illustrated on the second image data or the first imagedata in block 188, as discussed above.

After illustrating the position of the implant 120 on the image data,such as the first image data or model formed using the first image datain block 188, the method can end in END block 154. As discussed above,the imaging system 12 can be used to acquire the second image data toassist in illustrating a location of the implant for confirmation of aplanned procedure. Further the illustration of the implant based uponthe second image data can assist the user 54 in determining whetheradditional procedure steps, such as surgical steps, may be selected tobe performed to achieve a plan or augment the plan based upon the user'sexpertise. Accordingly, the second image data is used to assist inperforming a procedure on the patient 14 to either achieve a plan orachieve a selected result. It is understood, however, that the secondimage data can be acquired of any appropriate subject and need not belimited to a human subject as illustrated in FIG. 1 .

The method illustrated in FIG. 2 , therefore, allows for acquiring asecond image data without acquiring a complete set of image data. As isunderstood by one skilled in the art, a selected amount of image data(such as a complete set) can be used to generate a three dimensionalmodel of the patient 14. The first image data acquired in block 106 canbe enough image data to generate a selected quality of a model of thepatient 14. The amount of the first image data, therefore, may includeacquiring at least 300 projections of the patient 14 as the x-ray beam(between the source 26 and the detector 28) move arounds the patient 14via the gantry 20. The second image data may include a singleacquisition of multiple acquisitions, but both generally being less thanthe first image data acquisition projections. For example, a test imagedata acquisition may include about 1 to about 3 projections. The secondimage data (based on the test image data or not) may then include about10 projections or less at oblique angles around the patient 14, such asby moving a x-ray beam. The second image data, however, may be optimizedto view angles to register or verify the position of the implantedhardware relative to a prior image data, such as pre-operative imagedata including in the first image data. Therefore, the second image datacan be minimized relative to the first image data yet still allow forproviding image data for confirmation of a selected plan or assisting incompleting a surgical procedure on the patient 14 as discussed above.

The second image data (acquired in either blocks 176 or 302) may be theonly data used to determine the position of the pedicle screws 120 (orother members that are imaged). Further, the second image data may bethe only data used to determine the position of the members relative tothe first image data from block 106 or a model formed therefrom in block112. Thus, the second image data may be used without or in the absenceof tracking information to confirm a position of the members 120relative to the patient 14. Also, as discussed above, the position ofthe members determined in block 182 may be illustrated or superimposedon the first image data from block 106 or model from block 112.

Further, the members 120 need not be placed in a hard tissue, such as aboney tissue. The member that is implanted may be placed into softtissue, such as a deep brain stimulation probe or electrode. Theplacement of the electrodes may be planned and image data may beacquired after a selected portion of the procedure. A position of themember may be determined in a second image data and an icon representingthe member may be superimposed as discussed above. Further, the imagingdevice may be tracked and/or a test image may be acquired to determine aposition of the imaging device for acquiring second image data. Thus,one skilled in the art will understand that the member placed in thesubject need not be placed in hard or boney tissue.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention. Individual elements or features ofa particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the invention, and all such modificationsare intended to be included within the scope of the invention.

What is claimed is:
 1. A method of confirming at least a portion of aprocedure with image data acquired with an imaging device, comprising:moving the imaging device to a selected position relative to a portionof interest; acquiring confirmation image data of the portion ofinterest; determining a position of a member within the confirmationacquired image data; and superimposing an icon representing the memberat the determined position on a model of the portion of interestgenerated with a prior acquired image data, wherein the prior acquiredimage data is acquired prior to the confirmation image data.
 2. Themethod of claim 1, further comprising: tracking a position of the memberinto the portion of interest; and tracking a position of the imagingdevice relative to the portion of interest.
 3. The method of claim 2,wherein tracking the position of the imaging device relative to theportion of interest includes: tracking a detector of the imaging devicewhile moving the detector to a first position relative to the portion ofinterest for acquiring confirmation image data of the portion ofinterest and the member; and tracking the detector of the imaging devicewhile moving the detector to a second position relative to the portionof interest for acquiring confirmation image data of the portion ofinterest and the member.
 4. The method of claim 3, wherein tracking thedetector includes: recalling from a memory system a saved position ofthe imaging device during at least a portion of time when acquiring theprior acquired image data; determining a position of the detector toacquire unobstructed image data of the member in a first projection toallow determining the position of the member within the acquiredconfirmation image data; instructing the detector to move to thedetermined position; wherein both the prior acquired image data and theconfirmation image data may include a plurality of projections, whereineach of the plurality of projections is at a different position of thedetector.
 5. The method of claim 4, further comprising: executinginstructions with a processing unit to generate the model of the portionof interest generated with the prior acquired image data; and executinginstructions with the processing unit to model the position of themember for superimposing the icon representing the member at thedetermined position on the model of the portion of interest.
 6. Themethod of claim 1, further comprising: acquiring a test image of atleast a first portion of the portion of interest including the member;evaluating the acquired test image by extracting member from theacquired test image data; determining a position of the member withinthe portion of interest based only on the evaluation of the acquiredtest image; and executing instructions with a processing unit based onthe determined position of the member to determine at least one positionfor the acquiring confirmation image data of the portion of interest toat least minimize overlap of at least one of different implants ordifferent anatomical features.
 7. The method of claim 6, whereinexecuting instructions with the processing unit to determine at leastone position for acquiring confirmation image data of the portion ofinterest based on the determined position of the member includesdetermining the position of the imaging device to acquire anunobstructed view of the member.
 8. The method of claim 6, whereinmoving the imaging device to the selected position relative to a portionof interest is based on executing instructions with a processing unit todetermine at least one position for acquiring confirmation image data ofthe portion of interest based on the determined position of the member.9. The method of claim 6, further comprising: executing instructionswith the processing unit to determine the position of the iconsuperimposed on the model.
 10. The method of claim 9, furthercomprising: displaying with a display device the model with the iconsuperimposed thereon.
 11. The method of claim 1, wherein determining theposition of the member within the acquired confirmation image dataincludes determining the position of the member relative to the modelbased only the acquired confirmation image data.
 11. A system forconfirming at least a portion of a procedure with image data,comprising: an imaging device configured to be moved to a selectedposition relative to a portion of interest of a subject and acquireconfirmation image data of the portion of interest of the subject; aprocessor system configured to execute instructions to: evaluate theacquired confirmation image data of the portion of interest of thesubject acquired with the imaging device, and determine a position of amember based on the acquired confirmation image data of the portion ofinterest of the subject; and a display device configured to display anicon representing the member superimposed on an image at the determinedposition on the image of the portion of interest generated with a prioracquired image data, wherein the prior acquired image data is acquiredprior to the confirmation image data.
 12. The system of claim 11,further comprising: the member configured to be imaged with the imagingdevice at the portion of interest in the subject.
 13. The system ofclaim 12, further comprising: a navigation system having a trackingsystem configured to track a first tracking device associated with theimaging device and a second tracking device associated with the subject.14. The system of claim 13, further comprising: a memory systemconfigured to store a relative position of the imaging system and theportion of interest while acquiring the prior image data.
 15. The systemof claim 14, wherein the processor system is further configured toexecute instructions to: recall the stored relative position of theimaging system and the portion of interest while acquiring the priorimage data; and determine at least one position of the imaging device toacquire the confirmation image data of the member that is unobstructedimage data based at least one of the recalled stored relative positionof the imaging system, the portion of interest while acquiring the priorimage data, or a tracked position of the member.
 16. The system of claim12, wherein the processing system is further configured to executeinstructions to: evaluate a first test image data to identify themember; and determine at least one position of the imaging device toacquire the image data of the portion of interest acquired with theimaging device.
 17. The system of claim 11, wherein the processingsystem is further configured to execute instructions to determine theposition of the member based only on the acquired confirmation imagedata of the portion of interest of the subject.
 18. A method ofconfirming at least a portion of a procedure with image data acquiredwith an imaging device, comprising: acquiring a first image data of atleast a portion of interest of a subject with the imaging device at afirst position relative to the subject; moving the imaging device fromthe first position; operating a first processing unit to determine asecond position of the imaging device relative to at least the portionof interest of the subject to acquire a second image data after a memberhas been implanted into the subject; moving the imaging device to thesecond position relative to the portion of interest; acquiring thesecond image data of the portion of interest with the imaging device atthe second position; operating a second processing unit to: (i)determine a position of a member within the acquired second image data,and (ii) determine a first image data position of the member based onthe determined position of the member within the acquired second imagedata; and viewing a display of an icon superimposed on the first imagedata representing the member at the determined first image dataposition.
 19. The method of claim 18, wherein the first image dataincludes a model of the portion of interest of the subject and the iconis superimposed on the model.
 18. The Method of claim 18, furthercomprising: storing coordinates of the first position of the imagingdevice; and recalling the stored coordinates of the first position;wherein operating the first processing unit to determine the secondposition of the imaging device relative to at least the portion ofinterest of the subject to acquire the second image data is based atleast on the recalled stored coordinates.